Disk apparatus

ABSTRACT

A disk apparatus includes a base including a bottom wall and a sidewall disposed along a peripheral portion of the bottom wall, a cover including a ceiling plate and a side plate disposed along a periphery of the ceiling plate, the ceiling plate being fixed to the sidewall and the side plate facing an outer surface of the sidewall, and a rotatable recording medium disposed between the cover and the bottom wall. The sidewall of the base includes a first portion adjacent to the recording medium and a protruding portion that protrudes from the first portion outward and away from the recording medium, and at least a portion of a sidewall of the protruding portion faces an opening formed in the side plate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/694,720, filed Sep. 1, 2017, which application is based upon andclaims the benefit of priority from Japanese Patent Application No.2017-057089, filed Mar. 23, 2017, the entire contents of which areincorporated herein by reference.

FIELD

Embodiments described herein relate generally to a disk apparatus.

BACKGROUND

A hard disk drive (HDD) that functions as a disk apparatus includes arectangular casing, a disk-like recording medium disposed within thiscasing, and a magnetic head disposed within the casing for reading orwriting data from or to the recording medium. The casing includes arectangular base, a plate-like top cover screwed onto the base, and apacking member (e.g., gasket) disposed between a peripheral portion ofthe base and the top cover.

In such an HDD, a portion of a sidewall of the base which is adjacent tothe magnetic disk is made thinner due to a dimensional restriction. AnHDD having a large height, in particular, has a sidewall that is thinand high. Owing to this, when the base that has such a sidewall isaluminum or the like, reliably forming the sidewall via die cast moldingis difficult. Furthermore, in the portion of the sidewall that isthinner in wall thickness, it is difficult to sufficiently secure awidth of a surface in contact with the gasket, which can make formationof an airtight seal problematic.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a hard disk drive (HDD)according to a first embodiment.

FIG. 2 is an exploded perspective view of the HDD.

FIG. 3A is a perspective view illustrating a rear surface side of a topcover of the HDD.

FIG. 3B is an exploded perspective view illustrating the top cover and agasket.

FIG. 4 is a cross-sectional view of the HDD taken along a line A-A ofFIG. 1.

FIG. 5 is a cross-sectional view of the HDD taken along a line B-B ofFIG. 1.

FIG. 6 is a plan view of the HDD illustrating an internal structure ofthe HDD.

FIG. 7 is a perspective view illustrating a notch portion of the topcover in an enlarged fashion.

FIG. 8 is a plan view illustrating a protruding portion of a base of theHDD.

FIG. 9 is a perspective view illustrating a casing of the HDD in apartially enlarged fashion.

FIG. 10 is a perspective view illustrating an HDD according to a secondembodiment.

FIG. 11 is a perspective view illustrating the HDD according to thesecond embodiment in a partially enlarged fashion.

FIG. 12 is a perspective view illustrating an HDD according to a thirdembodiment.

FIG. 13 is an exploded perspective view illustrating the HDD accordingto the third embodiment.

FIG. 14 is a perspective view illustrating an HDD according to a fourthembodiment.

DETAILED DESCRIPTION

Embodiments provide a disk apparatus with improved airtightness thatincludes a robust contact area with a sealing member.

In general, according to one embodiment, a disk apparatus includes abase including a bottom wall and a sidewall disposed along a peripheralportion of the bottom wall, a cover including a ceiling plate and a sideplate disposed along a periphery of the ceiling plate, the ceiling platebeing fixed to the sidewall and the side plate facing an outer surfaceof the sidewall, and a rotatable recording medium disposed between thecover and the bottom wall. The sidewall of the base includes a firstportion adjacent to the recording medium and a protruding portion thatprotrudes from the first portion outward and away from the recordingmedium, and at least a portion of a sidewall of the protruding portionfaces an opening formed in the side plate.

Disk apparatuses according to embodiments will be described hereinafterwith reference to the drawings.

It is noted that the disclosure is presented by way of example only andmatters which can be changed as appropriate without departing from thespirit of the disclosure and which could easily be conceived of fallwithin the scope of the present disclosure. Moreover, for clarity ofdescription, in the drawings, constituent elements are often illustratedschematically in widths, thicknesses, shapes, and the like, and are notnecessarily shown to scale. Further, the drawings are presented by wayof example only and are not intended to limit the reading of the presentdisclosure. Furthermore, in the specification and the drawings, similarelements to those already described with reference to the drawingsalready described are denoted by the same reference signs and are oftennot described in detail, as appropriate.

First Embodiment

A hard disk drive (HDD) serving as a disk apparatus according to a firstembodiment will be described in detail.

FIG. 1 is a perspective view illustrating the HDD according to the firstembodiment, and FIG. 2 is an exploded perspective view illustrating theHDD in an exploded fashion.

In the present embodiment, an example of a 2.5-inch HDD that includes amagnetic disk at a diameter of about 2.5 inches (63.5 mm) is described.As shown in FIGS. 1 and 2, the HDD includes a flat and rectangularcasing 10. The casing 10 includes a rectangular box-like base 12 havingan open upper surface and a rectangular plate-like top cover 14. The topcover 14 is screwed on the base 12 by a plurality of screws 17 to closean upper opening of the base 12. Furthermore, a damper 70 configuredwith a metal plate is bonded onto the top cover 14.

The base 12 includes a rectangular bottom wall 12 a and a sidewall 12 blocated along a periphery of the bottom wall 12 a, and the bottom wall12 a and the sidewall 12 b are formed integrally from a metallicmaterial such as aluminum or stainless steel. The sidewall 12 b of thebase includes a pair of long side walls 13 a facing each other and apair of short side walls 13 b facing each other. An accommodation groove15 is formed in an upper surface of an edge portion of the sidewall 12b, and can be a groove, notch or other indentation. In some embodiments,accommodation groove 15 is formed over the entire periphery of thesidewall 12 b.

The top cover 14 is formed into a rectangular lid shape generallyidentical in dimension to the bottom wall 12 a of the base 12 bystamping a metal plate at a thickness of, for example, 0.45 mm. The topcover 14 includes a rectangular ceiling plate 14 a, and a pair of longside plates 14 b and a pair of short side plates 14 c, each formed bybending a corresponding side edge portion of the ceiling plate 14 atoward the base 12. generally at a right angle. In some embodiments, theside plates 14 b and 14 c are each formed to have a height equal to orless than half a height of the sidewall 12 b of the base 12.

Through-holes 18 are formed at the four corner portions of the ceilingplate 14 a and at a position slightly offset from a centerpoint of eachlong side plate 14 b. The top cover 14 is fastened to the sidewall 12 bof the base 12 via the screws 17 that are inserted into thethrough-holes 18 and threaded into screw holes formed in the sidewall 12b of the base 12. That is, the top cover is screwed on both endportions, in a longitudinal direction, of the short side walls 13 b andgenerally central portions, in a longitudinal direction, of the longside walls 13 a of the base 12 by the screws 17. The long side plates 14b and the short side plates 14 c of the top cover 14 are disposed withinthe accommodation groove 15 of the sidewall 12 b.

FIG. 3A is a perspective view illustrating an inner surface side of thetop cover 14, and FIG. 3B is an exploded perspective view illustratingthe top cover 14 and a gasket 20.

As shown in FIGS. 2, 3A, and 3B, the frame-like gasket (which is onetype of packing member or sealing member) 20 is sandwiched between theupper end surface of the sidewall 12 b of the base 12 and an innersurface of the ceiling plate 14 a of the top cover 14. This gasket 20 isformed from, for example, a synthetic resin, and coated or adhesivelybonded onto an inner surface of the top cover 14. A thickness of thegasket 20 is larger than a gap between the top cover 14 and the base 12.FIG. 4 is a cross-sectional view of the HDD taken along a line A-A ofFIG. 1, and FIG. 5 is a cross-sectional view of the HDD taken along aline B-B of FIG. 1. As shown in FIGS. 4 and 5, when the top cover 14 isscrewed on the base 12, the gasket 20 is sandwiched between the topcover 14 and the sidewall 12 b of the base 12 and compressedtherebetween to maintain airtightness within the casing 10.

FIG. 6 is a plan view of the HDD illustrating an internal structure ofthe HDD. As shown in FIGS. 2 and 6, a recording medium which is, forexample, one magnetic disk 16, and a spindle motor 23 serving as a driveunit that supports and rotates the magnetic disk 16 are disposed withinthe casing 10. The spindle motor 23 is provided on the bottom wall 12 a.The magnetic disk 16 has, for example, a diameter of about 2.5 inches(63.5 mm) and has a magnetic recording layer on each of an upper surfaceand a lower surface. It is assumed that the 2.5-inch magnetic disk isnot limited to the magnetic disk having a diameter of 63.5 mm but mayinclude a magnetic disk at a diameter of 65 mm or more. The magneticdisk 16 is coaxially fitted into a hub (not shown) of the spindle motor23, clamped by a clamp spring 27, and fixed to the hub. The magneticdisk 16 is thereby positioned to be parallel to the bottom wall 12 a ofthe base 12. The magnetic disk 16 is rotated at a predetermined velocityby the spindle motor 23. Furthermore, within the casing 10, the magneticdisk 16 is positioned to be offset from the center of the base 12, inthe longitudinal direction, toward one of the short side walls 13 b. Themagnetic disk 16 is consequently closer to one of the short side walls13 b than to the other short side wall 13 b.

Also disposed within the casing 10 is a plurality of magnetic heads 19for reading or writing data from or to the magnetic disk 16 and acarriage assembly 22 supporting these magnetic heads 19 in such a mannerthat each magnetic head 19 is movable relative to the magnetic disk 16.Furthermore, also disposed within the casing 10 is a voice coil motor(hereinafter, referred to as “VCM”) 24 for revolving and positioning thecarriage assembly 22, a ramp load mechanism 25 for holding the magnetichead 19 at an unload position apart from the magnetic disk 16 when themagnetic head 19 moves to an outermost circumference of the magneticdisk 16, a latch mechanism 26 for holding the carriage assembly 22 at aretreat position when an impact or the like acts on the HDD, and aflexible printed circuit board (FPC) unit 21 mounting therein electroniccomponents such as a conversion connector. The carriage assembly 22, theVCM 24, the ramp load mechanism 25, the latch mechanism 26, and the FPCunit 21 are disposed in a space between the magnetic disk 16 and theother short side wall 13 b in the base 12.

According to the present embodiment, at least one long side wall 13 a ofthe base 12 of the casing 10, or each of the two long side walls 13 a,includes a first portion located adjacent to an outer peripheral portionof the magnetic disk 16 and a protruding portion 50 a protruding orbulging from this first portion outward away from the magnetic disk 16.Each long side plate 14 b of the top cover 14 includes a notch or anopening portion 60 a (shown in FIGS. 7 and 9) that is aligned with andaccommodates the protruding portion 50 a.

FIG. 7 is a perspective view illustrating the opening portion 60 a ofthe top cover 14, FIG. 8 is a plan view illustrating a portion of theprotruding portion 50 a of the base 12, and FIG. 9 is a perspective viewillustrating the protruding portion 50 a and the opening portion 60 a.As shown in FIGS. 1, 2, 6, and 8, each long side wall 13 a of the base12 includes the first portion that is adjacent to the outer peripheralportion of the magnetic disk 16 and the protruding portion 50 a of thefirst portion that is disposed proximate the magnetic disk 16. In thepresent embodiment, “being adjacent” indicates a state in which thefirst portion faces the outer peripheral portion of the magnetic disk 16with a small gap of about 1 mm present between the first portion and theouter peripheral portion thereof. The protruding portion 50 a protrudesor bulges outward (away from the magnetic disk 16) from an outer sidesurface of the long side wall 13 a. In a height direction of the longside wall 13 a, The protruding portion 50 a is disposed on an upper sideof the long side wall 13 a (i.e., on a side of long side wall 13 a thatis distal from the rectangular bottom wall 12 a and proximal to thedamper 70) and formed flush with an upper surface of the long side wall13 a. The protruding portion 50 a is formed to have a thickness greaterthan the height of each long side plate 14 b of the top cover 14. Insome embodiments, the thickness of protruding portion 50 a is also equalto or less than half a height of the long side wall 13 a.

As described above, the base 12 is formed into a rectangular shape, andthe longitudinal direction of the base 12 is parallel to the long sidewalls 13 a and a width direction thereof is parallel to the short sidewalls 13 b. As shown in FIGS. 6 and 8, the two protruding portions 50 adisposed on the pair of long side walls 13 a are each located at aposition crossed by a straight line C that passes through a center ofthe magnetic disk 16 and is parallel to the short side walls 13 b of thebase 12. In the present embodiment, each protruding portion 50 a isformed to extend or protrude outward from the magnetic disk 16 along thestraight line C at an equal distance in each direction. A length L(shown in FIG. 8) of the protruding portion 50 a along the longitudinaldirection of the long side walls 13 a is, for example, about 16 mm.

A bulging amount of each protruding portion 50 a is set such that theprotruding portion 50 a extends beyond a long side edge of the ceilingplate 14 a of the top cover 14, and a width W between the two protrudingportions 50 a (see FIG. 6) is the maximum width of the base 12 and setto be larger than a width of the top cover 14. It is noted that thewidth W is set within a range of an outer shape dimension standard (forexample, SFF standard) of the HDD. In a case of the 2.5-inch HDD, thewidth W is set to 69.85±0.25 mm and the maximum width W of the base 12is, therefore, set to be equal to or smaller than 70.1 mm.

The above-described configuration of the protruding portions 50 aenables the upper end surface (i.e., the surface that contacts gasket20) of each long side wall 13 a in each of the protruding portions 50 ato have a larger width, as shown in FIG. 4. The above-describedconfiguration of the protruding portions 50 a also enables the upper endsurface to have the width set equal to or larger than that of otherportions of the long side wall 13 a.

As shown in FIGS. 2, 3A, 3B, 4, and 6, the gasket 20 includes curvedportions 20 a at positions respectively corresponding to the protrudingportions 50 a of the long side walls 13 a, and therefore bent or curveoutward along the protruding portions 50 a. That is, each curved portion20 a is in contact with a respective protruding portion 50 a. Therefore,the gasket 20 abuts on a central portion, in the width direction, of theupper end surface of the sidewall 12 b, including in the protrudingportions 50 a of the sidewall 12 b.

On the other hand, as shown in FIGS. 2, 3A, 3B, and 7, the notches oropening portions 60 a formed in the long side plates 14 b of the topcover 14 are located at positions corresponding to the two protrudingportions 50 a, respectively. That is, the two notches or openingportions 60 a are each located at the position crossing the straightline C passing through the center of the magnetic disk 16 and parallelto the short side walls 13 b of the base 12. Each notch or openingportion 60 a is formed to extend away longitudinally from the straightline C in both directions equally, so that the straight line C passesthrough a center portion of each opening portion 60 a. A length D ofeach opening portion 60 a along the longitudinal direction of the longside walls 13 a is formed to be equal to or smaller than 20 mm (D≤20mm), for example 16 mm, while a height of the opening portion 60 a isequal to the height of the long side plates 14 b.

As shown in FIGS. 1 and 9, in a state of screwing the top cover 14 onthe sidewall 12 b of the base 12, each of the protruding portions 50 aof the base 12 is accommodated in the opening portion 60 a of each ofthe long side plates 14 b of the top cover 14, and extends outwardthrough the opening portion 60 a in the long side plate 14 b. That is,the long side plate 14 b of the top cover 14 faces the sidewall 12 bexcept for the protruding portion 50 a. At the same time, as shown inFIG. 4, the gasket 20 is sandwiched between the ceiling plate 14 a ofthe top cover 14 and the upper end surface of the sidewall 12 b andtherefore is compressed between in the protruding portions 50 a and theupper end surface of the sidewall 12 b to maintain airtightness alongthe protruding portion 50 a.

In the HDD configured as described above, as the length D of each notchor opening portion 60 a of the top cover 14 is set larger, then rigidityof the top cover 14 degrades and the top cover 14 is prone to bulge by areaction force generated during compression of the gasket 20. Owing tothis, a substantial gasket compressibility degrades. According to asimulation, when the length D of the opening portion 60 a exceeds 20 mm,then an actual gasket compression amount becomes equal to or smallerthan half a desired gasket compression amount, and the airtightnessensured by the gasket is impaired. It is, therefore, preferable that thelength D of the opening portion 60 a of the top cover 14 satisfies D≤20mm. In the present embodiment, the length D is set to satisfy D=16 mm asdescribed above. Moreover, the width of the base 12 is increased withina range not exceeding the outer shape dimension standard of the 2.5-inchHDD in conformity to the opening portion 60 a.

According to the present embodiment, the HDD includes the damper 70provided on the top cover 14 as shown in FIGS. 1 and 2. The damper 70 isconfigured with the metal plate such as a stainless steel plate. Thedamper 70 is formed into a circular arc shape or a C-shape. The damper70 is thicker than the top cover 14.

As shown in FIGS. 2 to 4, the ceiling plate 14 a of the top cover 14includes a first recess portion 72 recessed toward the base 12 andhaving a circular arc shape or a generally C-shape, and a secondprojecting portion 74 protruding in a direction away from the base 12.The first recess portion 72 and the second projecting portion 74 can beformed simultaneously when the top cover 14 is pressed or stamped intoshape. Except for a region facing a central portion of the spindle motor23, the first recess portion 72 is formed to surround this centralportion. Furthermore, the first recess portion 72 is formed in a regionfacing a surface of the magnetic disk 16 except for a moving path ofeach magnetic head 19. Providing such a first recess portion 72 canreduce the size of a gap between the top cover 14 and the surface of themagnetic disk 16. Moreover, the second projecting portion 74 is formedin a region facing a central portion of the magnetic disk 16, the movingpath of each magnetic head 19, the carriage assembly 22, the VCM 24, theramp load mechanism 25, the latch mechanism 26, and the like.

The damper 70 has a shape that is identical or similar to that of thefirst recess portion 72 and is disposed within the first recess portion72. The damper is bonded onto the top cover 14 by, for example,adhesive. The damper 70 is disposed to face the surface of the magneticdisk 16. The damper 70 reinforces the top cover 14 and acts to damp avibration of the top cover 14 resulting from rotation of the magneticdisk 16.

In the present embodiment, the damper 70 includes a pair of side edgeportions 70 a located adjacent to the opening portions 60 a of the topcover 14, respectively. Likewise, the first recess position 72 includesa pair of bent side edge portions (or stepped portions) 72 a locatedadjacent to the opening portions 60 a of the top cover 14, respectively.As shown in FIGS. 1 to 3A, 4, 7, and 9, the side edge portions 70 a andthe drawn side edge portions 72 a of the first recess portion 72 of thedamper 70 are adjacent to the gasket 20 and extend generally in parallelto the gasket 20. In the present embodiment, regions of the side edgeportions 70 a and the bent side edge portions 72 a, which face thecurved portions 20 a of the gasket 20, are each formed into a circulararc shape that is concentric with each curved portion 20 a. The damper70 and the bent side edge portions 72 a reinforce regions including theopening portions 60 a of the top cover 14.

The HDD configured as described so far is capable of increasing thewidth of each thin wall portion of the sidewall 12 b of the base 12 tonearly an upper limit of a restriction on an apparatus outer shapedimension and thereby increase the thickness of the sidewall 12 b byproviding the protruding portions 50 a in the thin wall portion thereof.Furthermore, forming the protruding portions 50 a by machining canreduce a dimensional tolerance, so that it is possible to expect furtherincrease in the thickness of the sidewall 12 b. Increasing the thicknessof the sidewall 12 b can contribute to improving castability of the base12. Moreover, the width of a contact surface (upper end surface of thesidewall 12 b) with the gasket 20 increases and a contact area with thegasket 20 increases, so that it is possible to improve the airtightnessof the casing 10. Further, in the present embodiment, three screw holesare formed in each long side wall 13 a of the base 12, and a distancebetween the central screw hole and the screw hole formed in the endportion of the long side wall 13 a in the longitudinal direction andcloser to the magnetic disk 16 is larger than the distance between thecentral screw hole and the screw hole formed in the end portion of thelong side wall 13 a in the longitudinal direction and closer to thecarriage assembly 22. The protruding portion 50 a of each long side wall13 a is disposed between the screw holes separated by the largerdistance, so the protruding portions 50 a enable improved airtightnessof a region between these more widely separated screw holes.

Furthermore, bonding the damper 70 onto the top cover 14 can increase amechanical strength of the top cover 14, and it is possible for thedamper 70 to reinforce, in particular, the strength of the top cover 14that may be reduced by the presence the opening portions 60 a. Accordingto the present embodiment, providing the side edge portions 70 a of thedamper 70 and the drawn side edge portions 72 a of the first recessportion 72 of the ceiling plate 14 a of the top cover 14 near therespective opening portions 60 can increase the mechanical strength ofthe top cover 14 around the opening portions 60 a. Owing to this, whenthe gasket 20 is sandwiched between the top cover 14 and the base 12, itis possible to prevent or reduce deformation of the top cover 14 by thereaction force of the gasket 20, ensuring hermeticity of the casing 10.

In light of the foregoing, according to the present embodiment, it ispossible to obtain a hard disk drive that has a sufficiently robustcontact area between the gasket and the casing that improves theairtightness of the casing.

In the first embodiment, the shape of the damper 70 is not limited tothat described above and various other shapes are applicable as theshape of the damper 70. The number of the magnetic disks 16 is notlimited to one and can be increased as needed.

HDDs according to other embodiments will next be described. In the otherembodiments described below, the same constituent elements as those inthe above-mentioned first embodiment are denoted by the same referencenumbers and are not described in detail or are briefly described, andconstituent elements different from those in the first embodiment willbe mainly described.

Second Embodiment

FIG. 10 is a perspective view illustrating an appearance of the HDDaccording to a second embodiment, and FIG. 11 is a perspective viewillustrating the HDD in a partially enlarged fashion.

As shown in FIGS. 10 and 11, in the second embodiment, the damper 70includes a pair of side edge portions 70 a extending along long sides ofthe top cover 14, respectively. These side edge portions 70 a arepositioned to overlap regions of the gasket 20 and of the openingportions 60 a of the top cover 14. A length L of each side edge portion70 a along each long side of the top cover 14 is formed at least equalto the length D of the opening portion 60 a. In the present embodiment,the length L of each side edge portion 70 a is set to be about 1.5 to 2times as large as the length D of the opening portion 60 a. Each sideedge portion 70 a extends outward away from the magnetic disk 16 to begenerally flush with the long side of the top cover 14. Each side edgeportion 70 a is thereby positioned to entirety overlap each openingportion 60 a.

In the second embodiment, other configurations of the HDD are the sameas those of the HDD according to the above-described first embodiment.

According to the second embodiment, configured as described above, theside edge portions 70 a of the damper can more strongly reinforce theregions near the opening portions 60 a of the top cover 14. As a result,it is possible to further ensure that the top cover 14 is pressed ontothe gasket 20 and improve the airtightness.

It is noted that the length L of each side edge portion 70 a of thedamper 70 is not limited to the length equal to or larger than thelength D of the opening portion 60 a but alternatively can be madesmaller than the length D of the opening portion 60 a. Covering at leastpart of the region near the opening portion 60 a with each side edgeportion 70 can increase the strength of the top cover 14.

Third Embodiment

FIG. 12 is a perspective view illustrating the HDD according to a thirdembodiment, and FIG. 13 is an exploded perspective view of the HDD.

As shown in FIGS. 12 and 13, in the third embodiment, one of the longside walls 13 a of the base 12 that constitutes the casing 10 includes asidewall portion adjacent to the latch mechanism 26 and a secondprotruding portion 50 b protruding or bulging from this sidewall portionoutward from the long side wall 13 a. The second protruding portion 50 bis otherwise similar in configuration to the protruding portions 50 a.Furthermore, a notch or a second opening portion 60 b accommodatingtherein the second protruding portion 50 b is formed in one of the longside plates 14 b of the top cover 14. A shape and a size of the secondopening portion 60 b are similar to those of the aforementioned openingportions 60 a. Moreover, the gasket 20 includes a second curved portion20 b at a position corresponding to the second protruding portion 50 bof the long side wall 13 a to extend to be bent or curved outward alongthe second protruding portion 50 b. The gasket 20 thereby contacts thecentral portion, in the width direction, of the upper end surface of thesidewall 12 b, including in the protruding portion 50 b of the sidewall12 b.

Other configurations of the HDD are the same as those of the HDDaccording to the first embodiment.

According to the third embodiment configured as described above,positioning of the second protruding portion 50 b on the long side wall13 a near the latch mechanism 26 can increase the thickness of thisportion and widen the sidewall 12 b of the base 12 in a range notexceeding the apparatus outer shape dimension standard. It is therebypossible to improve the castability of the base 12. Moreover, the widthof the contact surface (upper end surface of the sidewall 12 b) with thegasket 20 is increased, so that it is possible to improve theairtightness of the casing 10.

Fourth Embodiment

FIG. 14 is a perspective view illustrating the HDD according to a fourthembodiment.

As shown in FIG. 14, in the fourth embodiment, one of the long sidewalls 13 a of the base 12 that constitutes the casing 10 includes asidewall portion adjacent to the ramp load mechanism 25 and a thirdprotruding portion 50 c protruding or bulging from this sidewall portionoutward of the long side wall 13 a. The third protruding portion 50 cmay be similar in configuration to the protruding portions 50 a.Furthermore, a notch or a third opening portion 60 c accommodatingtherein the third protruding portion 50 c is formed in one of the longside plates 14 b of the top cover 14. A shape and a magnitude of thethird opening 60 c are similar to those of the aforementioned openingportions 60 a. Moreover, the gasket 20 includes a third curved portion(not shown) at a position corresponding to the third protruding portion50 c of the long side wall 13 a that extends or curves outward along thethird protruding portion 50 c. The gasket 20 thereby contacts thecentral portion, in the width direction, of the upper end surface of thesidewall 12 b, including in the third protruding portions 50 c of thesidewall 12 b.

Other configurations of the HDD are the same as those of the HDDaccording to the first embodiment.

According to the fourth embodiment configured as described above,positioning the third protruding portion 50 c on the long side wall 13 anear the ramp load mechanism 25 can increase the thickness of thisportion and widen the sidewall 12 b of the base 12 in a range notexceeding the apparatus outer shape dimension standard. It is therebypossible to improve the castability of the base 12. Moreover, the widthof the contact surface (upper end surface of the sidewall 12 b) with thegasket 20 is increased, so that it is possible to improve theairtightness of the casing 10.

The present disclosure is not limited to the above-mentioned embodimentsor modifications but the present disclosure can be embodied by modifyingthe constituent elements without departing from the spirit of thepresent disclosure in implementation. Furthermore, various inventionscan be embodied by combining a plurality of constituent elementsdisclosed in the above-mentioned embodiments as appropriate. Forexample, some of the constituent elements may be deleted from all theconstituent elements described in the embodiments. Moreover, theconstituent elements across the different embodiments may be combined asappropriate.

In the first embodiment described above, the protruding portion of thebase is disposed on each of the pair of long side wall; however, thepresent disclosure is not limited to the first embodiment, and theprotruding portion may be disposed only on one long side wall. In thiscase, it is similarly possible to achieve improvement in the castabilityand the airtightness of the casing 10. Moreover, in the secondembodiment and the third embodiment, the protruding portion may be thesecond protruding portion only or the third protruding portion only.

The number of the magnetic disks is not limited to one but may be two ormore, and the number of the magnetic heads may be also increased ordecreased in response to the number of the magnetic disks included inthe HDD. The size of the magnetic disk is not limited to 2.5 inches butmay be the other size. Materials, shapes, magnitudes, and the like ofthe constituent elements of the disk apparatus are not limited to thosein the above-mentioned embodiments but can be variously changed asneeded.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A disk apparatus comprising: a recording medium;a base comprising a bottom wall and a sidewall on the bottom wall, thesidewall comprising first and second portions, the first portionpositioned closer to the recording medium than the second portion; and acover provided on the base and comprising a side portion at a positioncorresponding to the second portion of the sidewall and a first openingat a position corresponding to the first portion of the sidewall.
 2. Thedisk apparatus according to claim 1, wherein the first position of thesidewall comprises a first protrusion protruding towards an outer sideof the base.
 3. The disk apparatus according to claim 2, wherein alength of the first opening is greater than a length of the firstprotrusion in a longitudinal direction of the base.
 4. The diskapparatus according to claim 3, wherein the length of the first openingis less than 20 mm.
 5. The disk apparatus according to claim 2, whereinthe sidewall of the base further comprises a second protrusionprotruding towards an outer side of the base.
 6. The disk apparatusaccording to claim 2, wherein the first protrusion protrudes along astraight line passing through a center of the recording medium andperpendicular to a longitudinal direction of the base.
 7. The diskapparatus according to claim 2, further comprising: a magnetic head; acarriage assembly supporting the head; and a latch mechanism configuredto latch the carriage assembly, wherein the sidewall of the basecomprises a second protrusion protruding towards an outer side of thebase in a third portion adjacent to the latch mechanism and, and thecover comprises a second opening at a position corresponding to thethird portion.
 8. The disk apparatus according to claim 1, wherein thecover comprises a second opening along a longitudinal direction of thecover.
 9. The disk apparatus according to claim 1, further comprising: asealing member between the cover and the sidewall of the base.
 10. Thedisk apparatus according to claim 9, wherein the cover further comprisesa damper.
 11. The disk apparatus according to claim 10, wherein thedamper is overlapped with the sealing member on the first portion of thesidewall.
 12. The disk apparatus according to claim 10, wherein thedamper comprises a side edge portion having a length greater than alength of the first opening in a longitudinal direction of the base. 13.The disk apparatus according to claim 10, wherein the cover comprises arecess portion in which the damper is provided, and the recess portioncomprises a side portion having a curved shape along a shape of thesealing member on the first portion of the sidewall.
 14. The diskapparatus according to claim 9, wherein the sealing member includes acurved portion that curves outward away from the recording medium andextends along the first protrusion.
 15. The disk apparatus according toclaim 9, wherein a thickness of the damper is greater than a thicknessof the cover.